A flap device of the type named in the introduction is known from DE 199 46 861 A1. The flap device has a housing which has precisely one inlet duct for each cylinder of the internal combustion engine. In addition, the flap device has a flap arrangement which has for each inlet duct a flap for varying the cross-section of the respective inlet duct through which a flow can pass.
In the known flap device, all the flaps together form an integral body in a single piece, which undertakes at the same time the function of the actuating shaft. The individual flaps in this flap device are configured as butterfly flaps, which are arranged centrally with respect to the flap pivot axis.
From EP 0 726 388 A1 another flap device is known, in which the housing for each cylinder of the internal combustion engine has two inlet ducts, wherein the flap arrangement has a flap for varying the cross-section through which a flow can pass only for every other inlet duct. For the actuation of the flaps, a common actuating shaft is provided, on which the individual flaps are arranged. For this, the actuating shaft has for each flap a projection on which the respective flap is arranged, whereby a favourable torque transmission is produced between the actuating shaft and the flap.
In the known flap device, the flaps can be configured as butterfly flaps arranged centrally with respect to the flap pivot axis or as flaps formed eccentrically with respect to the flap pivot axis, projecting from the integral actuating shaft.